Swollen Battery at a Crowded Bench
At a small repair counter in a busy market, a customer hands over a 4G handset whose back cover is lifting. The technician finds a lithium-polymer battery swollen to about 8 mm above the frame; the phone still powers on and shows 62% charge. The bench has one 6 A extension board feeding a 25 W soldering iron, a 700 W hot-air rework station, a 60 W lamp and a 65 W phone charger. The floor is tiled, and a half-litre bottle of IPA (isopropyl alcohol) stands open beside the iron. The technician's colleague suggests puncturing the battery 'to let the gas out' and then charging it to test the phone. The shop has no fire blanket, but there is a steel bucket with dry sand used for sweeping. The customer is waiting and wants the phone back within 30 minutes.
1. List, in order, the safety actions you take in the first ten minutes, and explain why each comes before the next.
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Stop and isolate the electrical supply. Switch off the extension board and unplug the iron and hot-air station. The open IPA and the hot iron are an ignition pair, and a live bench while hands are inside a swollen phone is an unnecessary risk.
Put on PPE and contain the battery. Nitrile gloves and safety glasses; place the battery in the steel tray with dry sand, away from paper, foam and the bench. Do not puncture, bend, charge or compress it. A swollen lithium-polymer cell has a damaged separator; a puncture can create an internal short and thermal runaway.
Remove the ignition source. Cap the IPA and move it to a cabinet.
Communicate. Tell the customer the battery is unsafe, the phone will not be charged or tested with it, and a replacement is needed. Give a written note.
Check the board load. 25 + 700 + 60 + 65 = 850 W, about 3.7 A at 230 V, within a healthy 6 A board; but do not daisy-chain boards and replace any board that is warm, cracked or has a broken earth. The immediate hazard is the battery and IPA, not the total load.
Do not test until a correct new battery is fitted. If the old battery heats, hisses or vents, evacuate, smother with sand or an appropriate extinguisher, and call for help.
2. The colleague says puncturing the battery 'lets the gas out' and then charging it will show whether the phone works. Evaluate this advice and state what you would say.
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The advice is dangerous and technically wrong. A swollen cell is swollen because gas has built up inside a sealed pouch; puncturing the pouch does not make it safe. It exposes lithium and electrolyte to air and moisture, can start a fire, and releases flammable and toxic gases. Charging a swollen cell adds more gas and heat and can trigger thermal runaway. Testing the phone is not worth the risk: use a known-good battery of the correct capacity and connector, and only after the old cell is isolated.
I would say: 'We do not puncture or charge swollen cells. It can catch fire and the gas is harmful. I will replace the battery and test with a good one.' If the colleague insists, I would escalate to the owner and record the refusal. If the cell starts hissing or smoking, everyone leaves the area, the sand is used to smother only if it is safe to do so, and the fire service is called. The customer should be told the same facts in simple language.
3. The customer wants the phone back within 30 minutes. What do you commit to, and what do you refuse?
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I commit to a safe assessment and, if the correct battery is in stock, a battery replacement and basic function test within the 30 minutes. I would first check the replacement battery's voltage and connector, fit it, check charging current and boot, then test call audio, touch and network. The old battery goes into the sand tray and is not returned loose to the customer; it should go to an e-waste or battery-recycling point.
I refuse to puncture, charge or compress the swollen battery, and I refuse to return the phone with that battery fitted as if it were safe. If no correct battery is in stock, I offer to keep the phone with the battery removed and isolated, give a written receipt, and ask the customer to return when the part arrives. I would not promise 30 minutes if the phone shows other faults after the battery swap. The customer gets a clear explanation: the delay is because a swollen lithium battery is a fire risk, not because of ordinary repair time.